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From J Chris Anderson <>
Subject Re: Question on selecting on reduce values
Date Mon, 07 Jun 2010 19:38:12 GMT

On May 31, 2010, at 9:55 AM, Aurélien Bénel wrote:

> Good evening,
> 2. I'm a bit confused by the impact of views implementation on request time. Isn't couchdb
supposed to cache partial reduce results (like it does for map results)?

yes, they are cached (on each btree innner node). However, when the start and end keys do
not line up exactly with the btree boundaries than the "final reduce" needs to be caluclated
for that key range. This typically means 1 reduce call per line of output in a group-reduce
query. Doing this in Erlang avoids interprocess overhead, hence the speedup.


> Regards,
> Aurélien

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